Substrate processing apparatus

ABSTRACT

A substrate processing apparatus capable of forming an oxide film on a substrate by forming a layer on the substrate by supplying a source gas into a process vessel accommodating the substrate via the first nozzle, and simultaneously supplying an oxygen-containing gas through a second nozzle and a hydrogen-containing gas through a first nozzle into the process vessel having an inside pressure thereof lower than atmospheric pressure; mixing and reacting the oxygen-containing gas with the hydrogen-containing gas in a non-plasma atmosphere within the process vessel to generate atomic oxygen; and oxidizing the layer with the atomic oxygen to change the layer into an oxide layer is disclosed.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This U.S. non-provisional patent application is a continuation of U.S.patent application Ser. No. 14/329,355, filed Jul. 11, 2014, which is acontinuation of U.S. patent application Ser. No. 13/666.272, filed Nov.1, 2012, which issued as U.S. Pat. No. 8,809,204 on Aug. 19, 2014, whichis a continuation of U.S. patent application Ser. No. 12/607,223, filedOct. 28, 2009, which issued as U.S. Pat. No. 8,367,557 on Feb. 5, 2013,which claims priority under 35 U.S.C. §119 of Japanese PatentApplications No. 2008-278089, filed on Oct. 29, 2008, and No.2009-178309, filed Jul. 30, 2009, in the Japanese Patent Office, theentire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing asemiconductor device, which includes a process of forming a thin film ona substrate, and a substrate processing apparatus.

2. Description of the Prior Art

A flash memory includes an electron accumulation region (floating gate)surrounded by an insulation film, and its operation principle is toperform a data write operation by exchange of electrons through a thintunnel oxide film and to retain the electrons and keep memorized datafor a long time by using insulation property of the thin tunnel oxidefilm. Even though no operation from the outside is performed, datastored in a flash memory may need to be retained as long as ten years,and a requirement for an insulation film surrounding a chargeaccumulation region, called a floating gate, is strict. In an interlayerdielectric film disposed between the floating gate and a control gatedesigned to control a memory cell operation, a stacked structure ofoxide film (SiO₂)/nitride film (Si₃N₄)/oxide film (SiO₂), generallycalled ONO, is used and it is expected to have a high leakage currentcharacteristic.

Conventionally, the formation of an SiO₂ insulation film in an ONOstacked structure has been performed at a high temperature around 800°C. through a Chemical Vapor Deposition (CVD) process by using an SiH₂Cl₂gas and an N₂O gas. However, since the device is further scaled down andthe capacity of the nitride film among the ONO stacked films is lowered,the adoption of a high dielectric constant film instead of the nitridefilm has been considered in order for ensuring capacity. To suppresscrystallization of the high dielectric constant film, it is necessary toform an SiO₂ insulation film formed on the high dielectric constant filmat a temperature lower than a forming temperature of the high dielectricconstant film.

In the case of forming the SiO₂ insulation film, as its formingtemperature is lowered, atoms other than silicon (Si) and oxygen (O)contained in a source used for film formation may remain as impuritieswithin the film. Hence, in the case of forming the SiO₂ insulation filmat a low temperature by using an organic source gas, there has been aproblem that carbon (C), hydrogen (H), nitrogen (N) and so on containedin organic source gas molecules remain as impurities within the SiO₂insulation layer.

In addition, in the case of using an inorganic source gas, there hasbeen a problem that hydrogen (H), chlorine (Cl) and so on contained in asource remain as impurities within the film. Since such impuritiessignificantly degrade the film quality of the formed insulation film,there is a need for a technology that can form a high-quality insulationfilm having a low within-film impurity concentration at a lowtemperature.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method ofmanufacturing a semiconductor device and a substrate processingapparatus, which are capable of solving the above-described problems andforming an insulation film having extremely low impurity concentrationsof carbon, hydrogen, nitrogen, chlorine and so on contained within thefilm at a low temperature.

According to an aspect of the present invention, there is provided amethod of manufacturing a semiconductor device, the method including:forming an oxide film on a substrate by alternately repeating: (a)forming an element-containing layer on the substrate by supplying asource gas containing an element into a process vessel accommodating thesubstrate; and (b) changing the element-containing layer to an oxidelayer by supplying an oxygen-containing gas and a hydrogen-containinggas into the process vessel having an inside pressure lower thanatmospheric pressure, reacting the oxygen-containing gas with thehydrogen-containing gas to generate oxidizing species containing oxygen,and oxidizing the element-containing layer by the oxidizing species.

According to another aspect of the present invention, there is provideda method of manufacturing a semiconductor device, the method including:forming an oxide film on a substrate by alternately repeating: (a)forming an element-containing layer on the substrate by supplying asource gas containing an element into a process vessel accommodating thesubstrate; and (b) changing the element-containing layer to an oxidelayer by supplying an oxygen-containing gas and a hydrogen-containinggas into the process vessel having an inside pressure lower thanatmospheric pressure, reacting the oxygen-containing gas with thehydrogen-containing gas to generate oxidizing species containing oxygen,and oxidizing the element-containing layer by the oxidizing species,wherein the hydrogen-containing gas is supplied into the process vesseltogether with the source gas in the step (a).

According to another aspect of the present invention, there is provideda substrate processing apparatus including: a process vessel configuredto accommodate a substrate; a heater configured to heat the inside ofthe process vessel; a source gas supply system configured to supplysource gas containing a predetermined element into the process vessel;an oxygen-containing gas supply system configured to supply oxygen gasor ozone gas as the oxygen-containing gas into the process vessel; ahydrogen-containing gas supply system configured to supply hydrogen gasor deuterium gas as the hydrogen-containing gas into the process vessel;a pressure regulation unit configured to regulate pressure inside theprocess vessel; and a controller configured to control the source gassupply system, the oxygen-containing gas supply system, thehydrogen-containing gas supply system, the pressure regulation unit, andthe heater so that an oxide film having a predetermined film thicknessis formed on the substrate by repeating a process of forming apredetermined element-containing layer on the substrate by supplying thesource gas into the process vessel accommodating the substrate, and aprocess of changing the predetermined element-containing layer to anoxide layer by supplying the oxygen-containing gas and thehydrogen-containing gas into the process vessel that is set belowatmospheric pressure, and so that the temperature of the substrate isset in a range from 400° C. or more to 700° C. or less when forming theoxide film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of a vertical type processfurnace of a substrate processing apparatus that is preferably used inan embodiment of the present invention, specifically illustrating alongitudinal sectional view of the process furnace.

FIG. 2 is a schematic configuration view of the vertical type processfurnace of the substrate processing apparatus that is preferably used inthe embodiment of the present invention, specifically illustrating anA-A′ sectional view of the process furnace illustrated in FIG. 1.

FIG. 3 illustrates a film-forming flow diagram of the currentembodiment.

FIG. 4A and FIG. 4B illustrate timing diagrams of gas supply in afilm-forming sequence of the current embodiment. Specifically, FIG. 4Aillustrates an example of intermittently supplying H₂ gas, and FIG. 4Billustrates an example of continuously supplying H₂ gas.

FIG. 5 illustrates a film-forming rate ratio of a silicon oxide filmformed by the sequence of the conventional art and a silicon oxide filmformed by the sequence of the current embodiment.

FIG. 6 illustrates a film thickness distribution uniformity ratio of asilicon oxide film formed by the sequence of the conventional art and asilicon oxide film formed by the sequence of the current embodiment.

FIGS. 7A to 7C illustrate SiO₂ deposition models in the sequence of theconventional art.

FIGS. 8A to 8C illustrate SiO₂ deposition models in the sequence of thecurrent embodiment.

FIG. 9A is a graph illustrating concentration of impurities (H, C, N,Cl) contained within a silicon oxide film formed by a general CVDmethod, and FIG. 9B is a graph illustrating concentration of impurities(H, C, N, Cl) contained within a silicon oxide film formed by thesequence of the current embodiment.

FIG. 10A is a SEM image illustrating the state of the wafer before thesilicon oxide film was formed by the silicon oxide film by the sequenceof the current embodiment, and FIG. 10B is a SEM image illustrating thestate of the wafer after the silicon oxide film was formed by thesequence of the current embodiment.

FIG. 11 is a graph showing the relationship between the within-waferfilm thickness uniformity and the temperature of the wafer.

FIG. 12 is a graph showing the relationship between the film thicknessof the silicon oxide film and the temperature of the wafer.

FIG. 13 is a graph showing the relationship between the film thicknessof the silicon oxide film and the temperature of the wafer.

FIG. 14A is a graph illustrating the concentrations of impurities (H, C,N, Cl) contained within the silicon oxide film when N₂ gas is used as apurge gas, and FIG. 14B is a graph illustrating the concentrations ofimpurities (H, C, N, Cl) contained within the silicon oxide film when Argas is used as a purge gas.

FIG. 15A is a schematic configuration view of a vertical type processfurnace of a substrate processing apparatus that is preferably used inanother embodiment of the present invention, and FIG. 15B is an A-A′sectional view of the process furnace illustrated in FIG. 15A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Conventionally, organic-based sources have been used to form an oxidefilm at a low temperature, but the inventors have been devoted toresearch on methods of forming an oxide film at a low temperature byusing inorganic-based sources. As a result, the inventors found outthat, when a process of forming a source adsorption layer or apredetermined element layer (hereinafter, referred to as a predeterminedelement-containing layer) on a substrate by supplying a source gascontaining a predetermined element into the process vessel accommodatingthe substrate, and a process of changing the predeterminedelement-containing layer formed on the substrate to an oxide layer bysupplying an oxygen-containing gas and a hydrogen-containing gas intothe process vessel that was set below the atmospheric pressure weredefined as 1 cycle, a silicon oxide film having a predetermined filmthickness could be formed on the substrate by performing the cycle atleast one or more times. Herein, the source adsorption layer includes adiscontinuous adsorption layer as well as a continuous adsorption layerof source molecules. The predetermined element layer includes adiscontinuous layer as well as a continuous layer made of apredetermined element, or a thin film formed by their overlapping.Meanwhile, the continuous layer made of the predetermined element mightbe called a thin film.

The process of forming the predetermined element-containing layer(source adsorption layer or predetermined element layer) on thesubstrate is performed under a condition where a CVD reaction occurs,and, at this time, the predetermined element-containing layer is formedin a range of less than 1 atomic layer to several atomic layers.Meanwhile, the layer of less than 1 atomic layer refers to an atomiclayer formed discontinuously.

Also, in the process of changing the predetermined element-containinglayer to the oxide layer, an oxidizing species containing oxygen isgenerated by reaction of the oxygen-containing gas and thehydrogen-containing gas at the inside of the process vessel that is setunder a pressure atmosphere less than the atmospheric pressure, and thepredetermined element-containing layer is oxidized by the oxidizingspecies and changed to the oxide layer. Such an oxidation process mayremarkably improve oxidizing power, compared with the case of supplyingthe oxygen-containing gas alone. That is, compared with the case ofsupplying the oxygen-containing gas alone, the remarkably improvementeffect of the oxidizing power may be obtained by adding thehydrogen-containing gas to the oxygen-containing gas under adepressurized atmosphere. The process of changing the predeterminedelement-containing layer to the oxide layer is performed under adepressurized atmosphere of non-plasma.

It was ascertained that if the oxide film was formed by theabove-described method, the film-forming rate and the within-substratefilm thickness uniformity were excellent, compared with the case of filmformation by the CVD method using the organic-based sources.

Furthermore, it was ascertained that the within-film impurityconcentration of the oxide film formed by the above-described method wasextremely lowered, compared with the case of film formation by the CVDmethod using the organic-based sources. Moreover, it was ascertainedthat the above-described method was excellent in the film-forming rate,the within-substrate film thickness uniformity, and the within-filmimpurity concentration, even though the organic-based source was used.

The present invention was made based on the findings the inventorsobtained. Hereinafter, an embodiment of the present invention will bedescribed with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a vertical type processfurnace of a substrate processing apparatus that is preferably used inan embodiment of the present invention. Specifically, FIG. 1 is alongitudinal sectional view illustrating a portion of the processfurnace 202. Also, FIG. 2 is an A-A′ sectional view of the processfurnace illustrated in FIG. 1. Meanwhile, the present invention is notlimited to the substrate processing apparatus in accordance with thecurrent embodiment, but may also be preferably applied to a substrateprocessing apparatus having a single wafer type process furnace, a hotwall type process furnace, or a cold wall type process furnace.

As illustrated in FIG. 1, the process furnace 202 is provided with aheater 207 as a heating unit (heating mechanism). The heater 207 iscylindrically shaped and is vertically installed in such a manner thatit is supported on a heater base (not shown) used as a holding plate.

At the inside of the heater 207, a process tube 203 as a reaction tubeis installed concentrically with the heater 207. The process tube 203 ismade of, for example, a heat-resistant material such as quartz (SiO₂) orsilicon carbide (SiC), and is formed in a cylindrical shape with aclosed top end and an opened bottom end. At a hollow part of the processtube 203, a process chamber 201 is formed. The process chamber 201 isconfigured to accommodate wafers 200 as substrates which arehorizontally positioned and vertically arranged in multiple stages by aboat 217 as described later.

At the lower side of the process tube 203, a manifold 209 is installedconcentrically with the process tube 203. The manifold 209 is made of,for example, stainless steel or the like and is formed in a cylindricalshape with opened top and bottom ends. The manifold 209 is engaged withthe process tube 203 and installed to support the process tube 203. Inaddition, an O-ring 220 a used as a seal member is installed between themanifold 209 and the process tube 203. Since the manifold 209 issupported on a header base, the process tube 203 is in a verticallyfixed state. A reaction vessel (process vessel) is configured by theprocess tube 203 and the manifold 209.

At the manifold 209, a first nozzle 233 a as a first gas introductionunit, a second nozzle 233 b as a second gas introduction unit, and athird nozzle 233 c as a third gas introduction unit are installed topass through a sidewall of the manifold 209. A first gas supply pipe 232a, a second gas supply pipe 232 b, and a third gas supply pipe 232 c areconnected to the first nozzle 233 a, the second nozzle 233 b, and thethird nozzle 233 c, respectively. In this manner, three gas supply pipesare installed as gas supply passages to supply a plurality of kinds ofprocess gases, for example, three kinds of process gases into theprocess chamber 201.

At the first gas supply pipe 232 a, a mass flow controller 241 a used asa flow rate controller (flow rate control unit) and a valve 243 a usedas an on-off valve are sequentially installed from the upstreamdirection. Furthermore, at the more downstream side than the valve 243 aof the first gas supply pipe 232 a, a first inert gas supply pipe 234 aconfigured to supply inert gas is connected. At the first inert gassupply pipe 234 a, a mass flow controller 241 c used as a flow ratecontroller (flow rate control unit) and a valve 243 c used as an on-offvalve are sequentially installed from the upstream direction. Moreover,at the leading end of the first gas supply pipe 232 a, the first nozzle233 a described above is connected. The first nozzle 233 a is installedupright in the upward stacking direction of the wafers 200, from thelower part to the upper part of the inner wall of the process tube 203,in a space having a circular arc shape between the wafer 200 and theinner wall of the process tube 203 constituting the process chamber 201.In the side surface of the first nozzle 233 a, gas supply holes 248 athrough which gas is supplied are installed. The gas supply holes 248 aformed from the lower part to the upper part have the same opening areaand are installed at the same pitches. A first gas supply system may bemainly configured by the first gas supply pipe 232 a, the mass flowcontroller 241 a, the valve 243 a, and the first nozzle 233 a, and afirst inert gas supply system is mainly configured by the first inertgas supply pipe 234 a, the mass flow controller 241 c, and the valve 243c.

At the second gas supply pipe 232 b, a mass flow controller 241 b usedas a flow rate controller (flow rate control unit) and a valve 243 bused as an on-off valve are sequentially installed from the upstreamdirection.

Furthermore, at the more downstream side than the valve 243 b of thesecond gas supply pipe 232 b, a second inert gas supply pipe 234 bconfigured to supply inert gas is connected. At the second inert gassupply pipe 234 b, a mass flow controller 241 d used as a flow ratecontroller (flow rate control unit) and a valve 243 d used as an on-offvalve are sequentially installed from the upstream direction. Moreover,at the leading end of the second gas supply pipe 232 b, the secondnozzle 233 b described above is connected. The second nozzle 233 b isinstalled upright in the upward stacking direction of the wafers 200,from the lower part to the upper part of the inner wall of the processtube 203, in a space having a circular arc shape between the wafer 200and the inner wall of the process tube 203 constituting the processchamber 201. In the side surface of the second nozzle 233 b, gas supplyholes 248 b through which gas is supplied are installed. The gas supplyholes 248 b formed from the lower part to the upper part have the sameopening area and are installed at the same pitches. A second gas supplysystem may be mainly configured by the second gas supply pipe 232 b, themass flow controller 241 b, the valve 243 b, and the second nozzle 233b, and a second inert gas supply system is mainly configured by thesecond inert gas supply pipe 234 b, the mass flow controller 241 d, andthe valve 243 d.

At the third gas supply pipe 232 c, a mass flow controller 241 e used asa flow rate controller (flow rate control unit) and a valve 243 e usedas an on-off valve are sequentially installed from the upstreamdirection.

Furthermore, at the more downstream side than the valve 243 e of thethird gas supply pipe 232 c, a third inert gas supply pipe 234 cconfigured to supply inert gas is connected. At the third inert gassupply pipe 234 c, a mass flow controller 241 fused as a flow ratecontroller (flow rate control unit) and a valve 243 f used as an on-offvalve are sequentially installed from the upstream direction. Moreover,at the leading end of the third gas supply pipe 232 c, the third nozzle233 c described above is connected. The third nozzle 233 c is installedupright in the upward stacking direction of the wafers 200, from thelower part to the upper part of the inner wall of the process tube 203,in a space having a circular arc shape between the wafer 200 and theinner wall of the process tube 203 constituting the process chamber 201.In the side surface of the third nozzle 233 c, gas supply holes 248 cthrough which gas is supplied are installed. The gas supply holes 248 cformed from the lower part to the upper part have the same opening areaand are installed at the same pitches. A third gas supply system may bemainly configured by the third gas supply pipe 232 c, the mass flowcontroller 241 e, the valve 243 e, and the third nozzle 233 c, and athird inert gas supply system is mainly configured by the third inertgas supply pipe 234 c, the mass flow controller 241 f, and the valve 243f.

Gas containing oxygen (oxygen-containing gas), for example, oxygen (02)gas, is supplied into the process chamber 201 from the first gas supplypipe 232 a through the mass flow controller 241 a, the valve 243 a, andthe first nozzle 233 a. That is, the first gas supply system isconfigured as an oxygen-containing gas supply system. In this case, atthe same time, inert gas may be supplied into the first gas supply pipe232 a from the first inert gas supply pipe 234 a through the mass flowcontroller 241 c and the valve 243 c.

In addition, gas containing hydrogen (hydrogen-containing gas), forexample, hydrogen (H₂) gas, is supplied into the process chamber 201from the second gas supply pipe 232 b through the mass flow controller241 b, the valve 243 b, and the second nozzle 233 b. That is, the secondgas supply system is configured as a hydrogen-containing gas supplysystem. In this case, at the same time, inert gas may be supplied intothe second gas supply pipe 232 b from the second inert gas supply pipe234 b through the mass flow controller 241 d and the valve 243 d.

Furthermore, source gas, that is, gas containing silicon as apredetermined element (silicon-containing gas), for example,hexachlorodisilane (Si₂Cl₆, abbreviated to HCD) gas, is supplied intothe process chamber 201 from the third gas supply pipe 232 c through themass flow controller 241 e, the valve 243 e, and the third nozzle 233 c.That is, the third gas supply system is configured as a source gassupply system (silicon-containing gas supply system). In this case, atthe same time, inert gas may be supplied into the third gas supply pipe232 c from the third inert gas supply pipe 234 c through the mass flowcontroller 241 f and the valve 243 f.

Meanwhile, in the current embodiment, the O₂ gas, the H₂ gas, and theHCD gas are supplied into the process chamber 201 through the differentnozzles, but, for example, the H₂ gas and the HCD gas may be suppliedinto the process chamber 201 through the same nozzle. In addition, theO₂ gas and the H₂ gas may be supplied into the process chamber 201through the same nozzle. As such, if the nozzle is commonly used for aplurality of kinds of gases, there are merits that can reduce the numberof nozzles and apparatus costs and can also facilitate maintenance.Meanwhile, in a film-forming temperature zone to be described later, theHCD gas and the H₂ gas do not react with each other, but the HCD gas andthe O₂ gas may react with each other. Hence, it is preferable that theHCD gas and the O₂ gas are supplied into the process chamber 201 throughthe different nozzles.

At the manifold 209, a gas exhaust pipe 231 is installed to exhaust theinside atmosphere of the process chamber 201. A vacuum pump 246 used asa vacuum exhaust device is connected to the gas exhaust pipe 231 througha pressure sensor 245 used as a pressure detector and an Auto PressureController (APC) valve 242 used as a pressure regulator (pressureregulation unit). Meanwhile, the APC valve 242 is an on-off valveconfigured to perform a vacuum exhaust and a vacuum exhaust stop of theprocess chamber 201 by opening and closing the valve and to perform apressure regulation by adjusting a valve opening degree. While operatingthe vacuum pump 246, the opening degree of the APC valve 242 isadjusted, based on pressure detected by the pressure sensor 245, inorder that the inside of the process chamber 201 is vacuum-exhausted toa predetermined pressure (vacuum degree). An exhaust system may bemainly configured by the gas exhaust pipe 231, the pressure sensor 245,the APC valve 242, and the vacuum pump 246.

At the lower side of the manifold 209, a seal cap 219 is installed as afurnace port lid that can air-tightly close the bottom end opening ofthe manifold 209. The seal cap 219 is configured so that it is broughtinto contact with the bottom end of the manifold 209 in a verticaldirection from a lower part. The seal cap 219 is made of, for example, ametal such as stainless steel and is formed in a disk shape. On the topsurface of the seal cap 219, an O-ring 220 b is installed as a sealmember contacting the bottom end of the manifold 209. At the side of theseal cap 219 opposite to the process chamber 201, a rotation mechanism267 is installed to rotate a boat 217 used as a substrate holding tooldescribed later. A rotation shaft 255 of the rotation mechanism 267passes through the seal cap 219 and is connected the boat 217. Therotation mechanism 267 is configured to rotate the boat 217 so that thewafers 200 are rotated. The seal cap 219 is configured so that it iselevated in a vertical direction by a boat elevator 115 used as anelevation mechanism installed vertically at the outside of the processtube 203. The boat elevator 115 is configured to elevate the seal cap219 so that the boat 217 is loaded into or unloaded from the processchamber 201.

The boat 217 used as a substrate holding tool is made of, for example, aheat-resistant material such as quartz or silicon carbide. The boat 217is configured to hold a plurality of wafers 200 at a horizontal positionin multiple stages, with their centers aligned. In addition, a heatinsulation member 218 made of, for example, a heat-resistant materialsuch as quartz or silicon carbide is installed at the lower part of theboat 217 and is configured to suppress heat transfer from the heater 207toward the seal cap 52. Meanwhile, the heat insulation member 218 may beprovided with a plurality of heat insulation plates made of aheat-resistant material such as quartz or silicon carbide, and a heatinsulation plate holder configured to hold the heat insulation plates ata horizontal position in multiple stages. At the inside of the processtube 203, a temperature sensor 263 is installed as a temperaturedetector. An electrified state of the heater 207 is controlled, based ontemperature information detected by the temperature sensor 263, in orderthat the inside temperature of the process chamber 201 is made to have adesired temperature distribution. The temperature sensor 263 isinstalled along the inner wall of the process tube 203 in thesubstantially same manner as the first nozzle 233 a, the second nozzle233 b, and the third nozzle 233 c.

A controller 280 used as a control device (control unit) is connected tothe mass flow controllers 241 a, 241 b, 241 c, 241 d, 241 e and 241 f,the valves 243 a, 243 b, 243 c, 243 d. 243 e and 243 f, the pressuresensor 245, the APC valve 242, the heater 207, the temperature sensor263, the vacuum pump 246, the rotation mechanism 267, the boat elevator115, and so on. The controller 280 controls the gas flow rateregulations of the mass flow controllers 241 a, 241 b. 241 c, 241 d, 241e and 241 f, the opening and closing operations of the valves 243 a, 243b, 243 c, 243 d, 243 e and 243 f, the opening and closing of the APCvalve 242 and the pressure regulation operations of the APC valve 242based on the pressure sensor 245, the temperature regulation of theheater 207 based on the temperature sensor 263, the start and stop ofthe vacuum pump 246, the rotating speed regulation of the rotationmechanism 267, the elevating operation of the boat 217 by the boatelevator 115, and so on.

Next, explanation will be given on a method of forming an oxide film asan insulation film on a substrate, which is one of semiconductor devicemanufacturing processes, by using the process furnace of the substrateprocessing apparatus. Meanwhile, in the following description, theoperations of the respective elements constituting the substrateprocessing apparatus are controlled by the controller 280.

FIG. 3 illustrates a film-forming flow diagram of the currentembodiment, and FIG. 4A and FIG. 4B illustrate timing diagrams of gassupply in a film-forming sequence of the current embodiment. In thefilm-forming sequence of the current embodiment, a process of forming asource adsorption layer or a silicon layer (hereinafter, referred to asa silicon-containing layer) on a substrate by supplying a source gascontaining silicon as a predetermined element into the process vesselaccommodating the substrate, and a process of changing thesilicon-containing layer formed on the substrate to a silicon oxidelayer by supplying an oxygen-containing gas and a hydrogen-containinggas into the process vessel that is set below the atmospheric pressureare defined as 1 cycle, and a silicon oxide film having a predeterminedfilm thickness is formed on the substrate by performing the cycle atleast one or more times. The source adsorption layer includes adiscontinuous adsorption layer as well as a continuous adsorption layerof source molecules. The silicon layer includes a discontinuous layer aswell as a continuous layer made of silicon, or a thin film formed bytheir overlapping. Meanwhile, the continuous layer made of silicon mightbe called a silicon thin film.

The process of forming the silicon-containing layer (source adsorptionlayer or silicon layer) on the substrate is performed under a conditionwhere a CVD reaction occurs, and, at this time, the silicon-containinglayer is formed in a range of less than 1 atomic layer to several atomiclayers. Meanwhile, the layer of less than 1 atomic layer refers to anatomic layer that is formed discontinuously.

Also, in the process of changing the silicon-containing layer to thesilicon oxide layer, an oxidizing species containing oxygen is generatedby the reaction of the oxygen-containing gas and the hydrogen-containinggas at the inside of the process vessel that is set under a pressureatmosphere less than the atmospheric pressure, and thesilicon-containing layer is oxidized by the oxidizing species andchanged to the silicon oxide layer. Such an oxidation process mayremarkably improve oxidizing power, compared with the case of supplyingthe oxygen-containing gas alone. That is, compared with the case ofsupplying the oxygen-containing gas alone, the remarkably improvementeffect of the oxidizing power may be obtained by adding thehydrogen-containing gas to the oxygen-containing gas under adepressurized atmosphere. The process of changing the silicon-containinglayer to the silicon oxide layer is performed under a depressurizedatmosphere of non-plasma. Meanwhile, the hydrogen-containing gas may besupplied intermittently as illustrated in FIG. 4A, that is, only duringthe process of changing the silicon-containing layer to the siliconoxide layer, or the hydrogen-containing gas may be supplied continuouslyas illustrated in FIG. 4B, that is, always during the repetition of theprocess of forming the silicon-containing layer on the substrate and theprocess of changing the silicon-containing layer to the silicon oxidelayer.

Details will be described hereinbelow. Meanwhile, in the currentembodiment. HCD gas that is the source gas containing silicon is used asthe source gas, O₂ gas is used as the oxygen-containing gas, and H₂ gasis used as the hydrogen-containing gas. Explanation will be given on anexample of forming a silicon oxide film (SiO₂ film) as an insulationfilm on a substrate according to the sequence of FIG. 4A

When a plurality of wafers 200 are charged into the boat 217 (wafercharge), as illustrated in FIG. 1, the boat 217 holding the plurality ofwafers 200 is lifted by the boat elevator 115 and loaded into theprocess chamber 201 (boat load). In this state, the seal cap 219 sealsthe bottom end of the manifold 209 through the O-ring 220 b.

The inside of the process chamber 201 is vacuum-exhausted to a desiredpressure (vacuum degree) by the vacuum pump 246. In this case, thepressure inside the process chamber 201 is measured by the pressuresensor 245, and the APC valve 242 is feedback controlled, based upon themeasured pressure (pressure regulation). In addition, the inside of theprocess chamber 201 is heated to a desired temperature by the heater207. In this case, the electrified state of the heater 207 is feedbackcontrolled, based upon temperature information detected by thetemperature sensor 263, in order that the inside of the process chamber201 is made to have a desired temperature distribution (temperatureregulation). Subsequently, the boat 217 is rotated by the rotationmechanism 267, whereby the wafers 200 are rotated. Thereafter, thefollowing four steps are carried out in sequence.

[Step 1]

The valve 243 e of the third gas supply pipe 232 c and the valve 243 fof the third inert gas supply pipe 234 c are opened, and HCD gas andinert gas (for example, N₂ gas) are supplied to the third gas supplypipe 232 c and the third inert gas supply pipe 234 c, respectively. Theinert gas flows through the third inert gas supply pipe 234 c, and itsflow rate is controlled by the mass flow controller 241 f. The HCD gasflows through the third gas supply pipe 232 c, and its flow rate iscontrolled by the mass flow controller 241 e. The flow-rate-controlledHCD gas is mixed with the flow-rate-controlled inert gas within thethird gas supply pipe 232 c, supplied into the heated and depressurizedprocess chamber 201 through the gas supply holes 248 c of the thirdnozzle 233 c, and then exhausted through the gas exhaust pipe 231(supply of HCD gas).

At this time, by appropriately regulating the APC valve 242, thepressure inside of the process chamber 201 is maintained below theatmospheric pressure, for example, at a pressure ranging of 10 Pa to1,000 Pa. The supply flow rate of the HCD gas controlled by the massflow controller 241 e, for example, is in a range of 10 sccm to 1,000sccm. Exposure time of the wafers 200 to the HCD gas, for example, is ina range of 1 second to 180 seconds. The temperature of the heater 207 isset so that the CVD reaction occurs within the process chamber 201. Thatis, the temperature of the heater 207 is set so that the temperature ofthe wafers 200 is in a range of 300° C. to 700° C., preferably 350° C.to 650° C. Meanwhile, if the temperature of the wafers 200 is below 300°C. the HCD is difficult to be adsorbed on the wafers 200. Furthermore,if the temperature of the wafers 200 is above 650° C., especially 700°C., the CVD reaction becomes strong and the uniformity is easilyworsened. Therefore, it is preferable that the temperature of the wafers200 is in a range of 300° C. to 700° C.

By supplying the HCD gas into the process chamber 201 under theabove-described conditions, an HCD adsorption layer or a silicon layer(hereinafter, referred to as a silicon-containing layer) is formed in arange of less than 1 atomic layer to several atomic layers on the wafer200 (base layer of the surface). Meanwhile, the HCD is surface-adsorbedon the wafer 200 to form the HCD adsorption layer. The HCD isself-decomposed and thus silicon molecules are deposited on the wafer200 to form the silicon layer.

If the thickness of the silicon-containing layer formed on the wafer 200exceeds several atomic layers, the oxidation action in the step 3 to bedescribed later does not reach the entire silicon-containing layer.Furthermore, the minimum value of the silicon-containing layer that canbe formed on the wafer 200 is less than 1 atomic layer. Therefore, it ispreferable that the thickness of the silicon-containing layer is in arange of less than 1 atomic layer to several atomic layers.

In addition to HCD, an inorganic source such as tetrachlorosilane (TCS,SiCl₄), dichlorosilane (DCS, SiH₂Cl₂) or monosilane (SiH₄), and anorganic source such as aminosilane-based tetrakisdimethylaminosilane(4DMAS, Si(N(CH₃)₂))₄), trisdimethylaminosilane (3DMAS,Si(N(CH₃)₂))_(3H)), bisdiethylaminosilane (2DEAS, Si(N(C₂H₅)₂)₂H₂) orbis(tertiary-butylamino)silane (BTBAS, SiH₂(NH(C₄H₉))₂) may be used asthe Si-containing source.

In addition to N₂ gas, a rare gas such as Ar, He, Ne, or Xe may be usedas the inert gas. Meanwhile, the use of the rare gas such as Ar or He,which is inert gas containing no nitrogen (N), may reduce N impurityconcentration within the formed silicon oxide film. Therefore, it ispreferable that the rare gas such as Ar or He is used as the inert gas.The same is applied to the steps 2, 3 and 4 described below.

[Step 2]

After forming the silicon-containing layer on the wafer 200, the supplyof the HCD gas is stopped by closing the valve 243 e of the third gassupply pipe 232 c. At this time, the APC valve 242 of the gas exhaustpipe 231 is opened, and the inside of the process chamber 201 isvacuum-exhausted by the vacuum pump 246 to eliminate the residual HCDgas from the inside of the process chamber 201. At this time, if theinert gas is supplied into the process chamber 201, the eliminationeffect of the residual HCD gas is further increased (removal of residualgas). The temperature of the heater 207 at this time is set so that thetemperature of the wafers 200 is in a range of 300° C. to 700° C.,preferably 350° C. to 650° C., which is the same as the step ofsupplying the HCD gas.

[Step 3]

After removing the residual gas from the inside of the process chamber201, the valve 243 a of the first gas supply pipe 232 a and the valve243 c of the first inert gas supply pipe 234 a are opened, and O₂ gasand inert gas are supplied to the first gas supply pipe 232 a and thefirst inert gas supply pipe 234 a, respectively. The inert gas flowsthrough the first inert gas supply pipe 234 a and its flow rate iscontrolled by the mass flow controller 241 c. The O₂ gas flows throughthe first gas supply pipe 232 a and its flow rate is controlled by themass flow controller 241 a. The flow-rate-controlled O₂ gas is mixedwith the flow-rate-controlled inert gas within the first gas supply pipe232 a, supplied into the heated and depressurized process chamber 201through the gas supply holes 248 a of the first nozzle 233 a, and thenexhausted through the gas exhaust pipe 231. At this time, the valve 243b of the second gas supply pipe 232 b and the valve 243 d of the secondinert gas supply pipe 234 b are opened, and H₂ gas and inert gas aresupplied to the second gas supply pipe 232 b and the second inert gassupply pipe 234 b, respectively. The inert gas flows through the secondinert gas supply pipe 234 b and its flow rate is controlled by the massflow controller 241 d. The H₂ gas flows through the second gas supplypipe 232 b and its flow rate is controlled by the mass flow controller241 b. The flow-rate-controlled H₂ gas is mixed with theflow-rate-controlled inert gas within the second gas supply pipe 232 b,supplied into the heated and depressurized process chamber 201 throughthe gas supply holes 248 b of the second nozzle 233 b, and thenexhausted through the gas exhaust pipe 231 (supply of O₂ gas and H₂gas). Meanwhile, the O₂ gas and the H₂ gas are supplied into the processchamber 201, without being activated by plasma.

At this time, by appropriately regulating the APC valve 242, thepressure inside of the process chamber 201 is maintained below theatmospheric pressure, for example, at a pressure ranging from 1 Pa to1,000 Pa. The supply flow rate of the O₂ gas controlled by the mass flowcontroller 241 a, for example, is in a range of 1 sccm to 20 slm. Thesupply flow rate of the H₂ gas controlled by the mass flow controller241 b, for example, is in a range of 1 sccm to 20 slm. Meanwhile,exposure time of the wafers 200 to the O₂ gas and the H₂ gas, forexample, is in a range of 1 second to 180 seconds. The temperature ofthe heater 207 is set so that the temperature of the wafers 200 is in arange of 350° C. to 1,000° C. Meanwhile, it was confirmed that when thetemperature was within the above range, the improvement effect of theoxidizing power was obtained by the addition of the H₂ gas to the O₂ gasunder the depressurized atmosphere. In addition, it was also confirmedthat when the temperature of the wafers 200 was too low, the improvementeffect of the oxidizing power was not obtained. However, if consideringthe throughput, it is preferable that the temperature of the heater 207is set so that the wafers 200 have the same temperature as that in thestep 1 of supplying the HCD gas, as a temperature where the improvementeffect of the oxidizing power can be obtained, that is, the inside ofthe process chamber 201 is kept at the same temperature in the step 1and the step 3. In this case, in the step 1 and the step 3, thetemperature of the heater 207 is set so that the temperature of thewafers 200, that is, the temperature inside the process chamber 201, isin a range of 350° C. to 700° C., preferably 350° C. to 650° C.Furthermore, it is more preferable that the temperature of the heater207 is set so that the inside of the process chamber 201 is kept at thesame temperature through the step 1 to step 4 (described later).

In this case, the temperature of the heater 207 is set so that thetemperature inside the process chamber 201 is constant within a range of350° C. to 700° C., preferably 3500 to 650° C. Meanwhile, to obtain theeffect of the oxidizing power improvement by the addition of the H₂ gasto the O₂ gas under the depressurized atmosphere, the temperature insidethe process chamber 201 needs to be 350° C. or more, and the temperatureinside the process chamber 201 is preferably 400° C. or more, and morepreferably 450° C. or more. When the temperature inside the processchamber 201 is 400° C. or more, it is possible to obtain the oxidizingpower exceeding the oxidizing power obtained by O₃ oxidation processperformed at a temperature of 400° C. or more. When the temperatureinside the process chamber 201 is 450° C. or more, it is possible toobtain the oxidizing power exceeding the oxidizing power obtained by O₂plasma oxidation process performed at a temperature of 450° C. or more.

By supplying the O₂ gas and the H₂ gas into the process chamber 201under the above-described conditions, the O₂ gas and the H₂ gas arenon-plasma activated under the heated and depressurized atmosphere andare reacted with each other to generate oxidizing species containing Osuch atomic oxygen. The oxidation process is performed primarily by theoxidizing species with respect to the silicon-containing layer formed onthe wafer 200 in the step 1. Due to the oxidation process, thesilicon-containing layer is changed to the silicon oxide layer (SiO₂layer, also simply called a SiO layer).

In addition to the oxygen (O₂) gas, ozone (O₃) gas may be used as theoxygen-containing gas. Meanwhile, when the additional effect of thehydrogen-containing gas to nitric oxide (NO) gas or nitrous oxide (N₂O)gas in the above-described temperature zone was tested, it was confirmedthat the effect of the oxidizing power improvement was not obtained,compared with the supply of NO gas alone or the supply of N₂O gas alone.That is, it is preferable that the oxygen-containing gas containing nonitrogen (gas that does not contain nitrogen but contains oxygen) isused as the oxygen-containing gas. In addition to the hydrogen (H₂) gas,deuterium (D₂) gas may be used as the hydrogen-containing gas.Meanwhile, if ammonia (NH₃) gas or methane (CH₄) gas may be used,nitrogen (N) impurity or carbon (C) impurity may be incorporated intothe film. That is, it is preferable that the hydrogen-containing gascontaining no other element (gas that does not contain other element butcontains only hydrogen) is used as the hydrogen-containing gas. That is,at least one gas selected from the group consisting of O₂ gas and O₃ gasmay be used as the oxygen-containing gas, and at least one gas selectedfrom the group consisting of H₂ gas and D₂ gas may be used as thehydrogen-containing gas.

[Step 4]

After changing the silicon-containing layer to the silicon oxide layer,the supply of the O₂ gas is stopped by closing the valve 243 a of thefirst gas supply pipe 232 a. Also, the supply of the H₂ gas is stoppedby closing the valve 243 b of the second gas supply pipe 232 b. At thistime, the APC valve 242 of the gas exhaust pipe 231 is opened, theinside of the process chamber 201 is vacuum-exhausted by the vacuum pump246, and the residual O₂ gas or H₂ gas is eliminated from the inside ofthe process chamber 201. In this case, if inert gas is supplied into theprocess chamber 201, the elimination effect of the residual O₂ gas or H₂gas is further increased (removal of residual gas). At this time, thetemperature of the heater 207 is set so that the temperature of thewafers 200 is in a range of 350° C. to 700° C., preferably 350° C. to650° C., which is the same as the step of supplying the O₂ gas and theH₂ gas.

The above-described steps 1 to 4 are defined as 1 cycle, and a siliconoxide film having a predetermined film thickness is formed on thesubstrate by performing the cycle at least one or more times.

After the silicon oxide film having the predetermined film thickness isformed, inert gas is supplied into and exhausted from the processchamber 201, so that the inside of the process chamber 201 is purgedwith the inert gas (purge). Thereafter, the atmosphere inside theprocess chamber 201 is replaced with the inert gas, and the pressureinside the process chamber 201 returns to the normal pressure (return toatmospheric pressure).

After that, the seal cap 219 is moved downward by the boat elevator 115,and the bottom end of the manifold 209 is opened. The boat 217 chargedwith the processed wafers 200 is unloaded from the bottom end of themanifold 209 to the outside of the process tube 203. Subsequently, theprocessed wafers 200 are discharged from the boat 217.

By performing the process of generating the oxidizing species containingO such as atomic oxygen through the reaction of the O₂ gas and the H₂gas under the heated and depressurized atmosphere, and changing thesilicon-containing layer to the silicon oxide layer by using theoxidizing species in the above-described step 3, energy of the oxidizingspecies breaks Si—N, Si—Cl, Si—H and Si—C bonds contained in thesilicon-contained layer. Since energy for forming Si—O bond is higherthan Si—N, Si—Cl, Si—H and Si—C bond energies, Si—N, Si—Cl, Si—H andSi—C bonds inside the silicon-contained layer are broken by applyingenergy necessary for Si—O bond formation to the silicon-containing layerto be oxidized. N. H, Cl, and C separated from the bond with Si areremoved from the film and are exhausted in a form of N₂, H₂, Cl₂, HCl,or CO₂. In addition, since the bonds with N, H. Cl, and C are broken,the remaining bonds of Si is connected to O contained in the oxidizingspecies and changes to an SiO₂ layer. It was confirmed that the SiO₂film formed by the film-forming sequence of the current embodiment was ahigh-quality film in which nitrogen, hydrogen, chlorine, and carbonconcentrations were extremely low, and the Si/O ratio was very close to0.5, which is a stoichiometric composition.

Meanwhile, as a result of comparing the oxidation process of the step 3with the O₂ plasma oxidation process and the O₃ oxidation process, itwas confirmed that the oxidizing power of the oxidation process of thestep 3 was strongest under the low temperature atmosphere of 450° C. ormore to 700° C. or less. To be exact, it was confirmed that theoxidizing power of the oxidation process of the step 3 exceeded theoxidizing power of the O₃ oxidation process at a temperature range of400° C. or more to 700° C. or less, and the oxidizing power of theoxidation process of the step 3 exceeded the oxidizing powers of the O₃oxidation process and the O₂ plasma oxidation process at a temperaturerange of 450° C. or more to 700° C. or less. Hence, it was ascertainedthat the oxidation process of the step 3 was very efficient under thelow temperature atmosphere.

Meanwhile, the O₂ plasma oxidation process requires a plasma generator,and the O₃ oxidation process requires an ozonizer. However, since theoxidation process of the step 3 does not require them, there is a meritthat can reduce apparatus costs. In the current embodiment, however,there is an alternative that may use O₃ or O₂ plasma as theoxygen-containing gas, and thus, the use of these gases is not denied.An oxidizing species having more higher energy may be generated byadding hydrogen-containing gas to the O₃ or O₂ plasma, and devicecharacteristics may be improved by performing the oxidation process withthe use of the oxidizing species.

In addition, it was confirmed that when the silicon oxide film wasformed by the film-forming sequence of the current embodiment, thefilm-forming rate and the within-wafer film thickness uniformity weremore excellent than the case of forming a silicon oxide film through ageneral CVD method. Meanwhile, the general CVD method refers to a methodof simultaneously supplying DCS, which is an inorganic source, and N₂Oand forming a silicon oxide film (high temperature oxide (HTO) film)through a CVD method. In addition, it was confirmed that concentrationof impurity such as nitrogen or chlorine within the silicon oxide filmformed by the film-forming sequence of the current embodiment wasextremely lower than the silicon oxide film formed by the general CVDmethod. Furthermore, it was confirmed that concentration of impuritywithin the silicon oxide film formed by the film-forming sequence of thecurrent embodiment was extremely lower than the silicon oxide filmformed by the CVD method using organic-based silicon source. Moreover,it was confirmed that the film-forming sequence of the currentembodiment was excellent in the film-forming rate, the within-wafer filmthickness uniformity, and the within-film impurity concentration, eventhough organic-based silicon source was used.

In the above-described embodiment, explanation has been given on theexample of intermittently supplying the H₂ gas as thehydrogen-containing gas, as illustrated in FIG. 4A, that is, the exampleof supplying the H₂ gas only in the step 3. However, the H₂ gas may becontinuously supplied, as illustrated in FIG. 4B, that is, the H₂ gasmay be always continuously supplied during the repetition of the step 1to the step 4. Also, in the case of intermittently supplying the H₂ gas,it may be supplied only in the step 1 and the step 3, or may be suppliedduring the step 1 to the step 3.

Moreover, the H₂ gas may be supplied over the step 2 to the step 3, ormay be supplied during the step 3 to the step 4.

Cl may be extracted from the HCD gas by supplying H₂ gas during thefirst step 1, that is, the supply of the HCD gas, and the improvement ofthe film-forming rate and the reduction effect of Cl impurity may beobtained. Also, the film thickness uniformity may be effectivelycontrolled by initiating the supply of H₂ gas in the step 2, that is,prior to the supply of O₂ gas after the stop of the supply of the HCDgas. Furthermore, an oxide film may be selectively formed on silicon,for example, with respect to a region where metal and silicon areexposed, by initiating the supply of H₂ gas in the step 2, that is,prior to the supply of O₂ gas. Moreover, the surface of the SiO layerformed in the step 3 is modified through hydrogen termination bysupplying H₂ gas in the step 4, that is, prior to the initiation of thesupply of the HCD gas after the stop of the supply of the O₂ gas, andthe HCD gas supplied in the next step 1 may be easily adsorbed on thesurface of the SiO layer.

First Embodiment

Next, a first embodiment will be described.

Silicon oxide films were formed by the sequence of the currentembodiment and the sequence of the conventional art, and theirfilm-forming rates and film-thickness distribution uniformities weremeasured. Meanwhile, the sequence of the conventional art is a sequencethat uses gas containing oxygen active species (O*) obtained by plasmaexcitation of O₂ gas, instead of using O₂ gas and H₂ gas in the step 3of the sequence of the current embodiment. Also, the film-formingcondition in the sequence of the current embodiment (process conditionin each step) was set within the condition range of the above-describedembodiment. With regard to the film-forming condition in the sequence ofthe conventional art (process condition in each step), the processconditions in the steps 1, 2 and 4 was the same as the sequence of thecurrent embodiment, and the process condition in the step 3 was asfollows: pressure inside the process chamber was in a range of 10 Pa to100 Pa, the supply flow rate of O₂ was in a range of 100 sccm to 10,000sccm, the supply time of O₂ gas was in a range of 1 second to 180seconds, the wafer temperature was in a range of 350° C. to 650° C., andhigh-frequency power was in a range of 50 W to 400 W.

The results are illustrated in FIG. 5 and FIG. 6. FIG. 5 illustrates thefilm-forming rate ratio of the silicon oxide film formed by the sequenceof the current embodiment, on the assumption that the film-forming rateof the silicon oxide film formed by the sequence of the conventional artis 1. FIG. 6 illustrates the within-wafer film thickness distributionuniformity ratio of the silicon oxide film formed by the sequence of thecurrent embodiment, on the assumption that the within-wafer filmthickness distribution uniformity of the silicon oxide film formed bythe sequence of the conventional art is 1. Meanwhile, the film thicknessdistribution uniformity represents the variation degree of thewithin-wafer film thickness distribution, and the within-wafer filmthickness uniformity is considered to be excellent as its value issmaller.

As illustrated in FIG. 5, it can be seen that the film-forming rate ofthe silicon oxide film formed by the sequence of the current embodimentis remarkably high, compared with the silicon oxide film formed by thesequence of the conventional art. It can be seen that the film-formingrate of the sequence of the current embodiment is five times higher thanthe film-forming rate of the sequence of the conventional art.Meanwhile, the film-forming rate when the silicon oxide film was formedby the sequence of the current embodiment was about 2 Å/cycle.

In addition, as illustrated in FIG. 6, it can be seen that the filmthickness distribution uniformity of the silicon oxide film formed bythe sequence of the current embodiment is remarkably improved, comparedwith the silicon oxide film formed by the sequence of the conventionalart. It can be seen that the sequence of the current embodiment obtainsvery excellent film thickness distribution uniformity corresponding toabout 1/20 of the film thickness distribution uniformity of the siliconoxide film formed by the sequence of the conventional art. Meanwhile,the film thickness distribution uniformity of the silicon oxide filmformed by the sequence of the current embodiment was about 1.5%.

Explanation will be given on the merit of the sequence of the currentembodiment that oxidizes the silicon-containing layer (HCD adsorptionlayer or silicon layer), which is formed on the substrate, by theoxidizing species containing O obtained by reaction of O₂ gas and H₂ gasunder the heated and depressurized atmosphere, instead of O* obtained byplasma excitation of O₂ like the sequence of the conventional art.

FIGS. 7A to 7C illustrate SiO₂ deposition models in the sequence of theconventional art, and FIGS. 8A to 8C illustrate SiO₂ deposition modelsin the sequence of the current embodiment. Meanwhile, the sequences showthe case of forming the adsorption layer of HCD as the source on thesurface of the silicon wafer in the step 1.

In the case of the sequence of the conventional art of FIGS. 7A to 7C,if HCD gas is supplied as a source gas, as illustrated in FIG. 7A. HCDis adsorbed on the surface of the silicon wafer, whereby an HCDadsorption layer is formed on the silicon wafer.

In such a state, if gas containing oxygen active species (O*) obtainedby plasma excitation of O₂ gas is supplied, as illustrated in FIG. 7B,the oxidation of the HCD molecules adsorbed on the surface of thesilicon wafer is performed from the upstream toward the downstream ofthe O₂ gas (O*) flow in the wafer surface. On the other hand, the HCDmolecules of the downstream of the O₂ gas flow in the wafer surface aredesorbed from the surface of the silicon wafer.

It is though that this is because O* obtained by the plasma excitationof the O₂ gas has energy enough to oxidize the HCD molecules and breakthe Si—O bond or the Si—Si bond. That is, in this case, fixation of Sion the surface of the silicon wafer is not sufficiently achieved, and Siis not fixed on the surface of the silicon wafer in some regions. Also,as illustrated in FIG. 7C, O* also oxidizes the surface of the siliconwafer, which is the base of the formed SiO₂ film.

For this reason, if the SiO₂ film is formed by the sequence of theconventional art, while rotating the silicon wafer, the film thicknessof the outer periphery of the SiO₂ film becomes thick, and the filmthickness distribution uniformity in the wafer surface is worsened (seeFIG. 6). Furthermore, the HCD molecules desorbed from the surface of thesilicon wafer flow to the downstream inside the process chamber, andthey are re-adsorbed on the wafers disposed at the downstream of the O₂gas flow inside the process chamber, that is, the lower part of thewafer arrangement area, and then are oxidized. Thus, the wafer-to-waferfilm thickness distribution uniformity may also be worsened.

On the contrary, in the case of the sequence of the current embodimentof FIG. 8, if the HCD gas is supplied, as illustrated in FIG. 8A, HCD isadsorbed on the surface of the silicon wafer, whereby an HCD adsorptionlayer is formed on the silicon wafer.

In such a state, if gas containing oxidizing species containing Oobtained by reaction of O₂ gas and H₂ gas under the heated anddepressurized atmosphere is supplied, as illustrated in FIG. 8B, theoxidation of the HCD molecules adsorbed on the surface of the siliconwafer is performed from the upstream toward the downstream of the O₂ gasand H₂ gas (oxidizing species) flow within the wafer surface. At thistime, the HCD molecules of the downstream of the O₂ gas and H₂ gas flowwithin the wafer surface are not desorbed from the surface of thesilicon wafer. That is, desorption of the HCD molecules from the surfaceof the silicon wafer, which has occurred in the sequence of theconventional art, is suppressed. In the case of using O₃ or O* obtainedby the plasma excitation of O₂ gas, extra energy applied to the siliconwafer breaks Si—O bond or Si—Si bond. On the other hand, in the case ofusing oxidizing species obtained by the reaction of O₂ gas and H₂ gasunder the heated and depressurized atmosphere, new energy is not appliedto the silicon wafer, but HCD molecules are oxidized by oxidizingspecies generated by the reaction of O₂ gas and H₂ gas in the vicinityof the silicon wafer. That is, in the case of the oxidation process ofthe current embodiment, oxidation is performed with the oxidizing powerhigher than that of the O₂ plasma oxidation process or O₃ oxidationprocess, and extra energy enough to break Si—O bond or Si—Si bond is notgenerated. In this case, since fixation of Si on the surface of thesilicon wafer is sufficiently carried out, Si is fixed uniformly on thesurface of the silicon wafer. Therefore, as illustrated in FIG. 8C, HCDmolecules adsorbed on the surface of the silicon wafer are oxidizeduniformly over the entire wafer surface and changed to an SiO₂ layer,and the SiO₂ layer is formed uniformly on the surface of the siliconwafer over the entire wafer surface. By repeating the above processes,the intra-wafer film thickness uniformity of the SiO₂ film formed on thewafer becomes excellent (see FIG. 6). Meanwhile, in the case of addingH₂ to O₂ plasma, oxidation by oxidizing species generated by reaction ofO₂ and H₂ is dominant. Also, in the case of adding H₂ to O₃, oxidationby oxidizing species generated by reaction of O₃ and H₂ is dominant.That is, in the case of using O₂ plasma or O₃, the same effect as theoxidation process of the current embodiment can be obtained by addingH₂.

Meanwhile, in the sequence of the conventional art of FIG. 7 and thesequence of the current embodiment of FIG. 8, the case of forming theHCD adsorption layer on the surface of the silicon wafer in the step 1has been described. The case where the HCD gas supplied in the firststep is self-decomposed and the silicon layer is formed on the surfaceof the silicon wafer may be considered as the same. In this case, if theHCD molecules of FIG. 7 and FIG. 8 are replaced with the Si molecules,the same explanation can be given.

Second Embodiment

Next, a second embodiment will be described.

Silicon oxide films were formed by the sequence of the currentembodiment and the general CVD method, and their within-film impurityconcentration were measured. Meanwhile, the general CVD method is amethod that forms a silicon oxide film (HTO film) by a CVD method bysupplying DCS and N₂O at the same time, and the film-forming temperaturewas 780° C. Also, in each step of the sequence of the currentembodiment, the film-forming temperature was constant at 600° C., andthe other film-forming conditions (process condition of each step) wereset within the condition ranges of the above-described embodiment. Also,the measurement of impurities inside the film was carried out by usingSIMS.

The results are illustrated in FIGS. 9A and 9B. FIG. 9A illustratesconcentration of impurities (H, C, N, Cl) contained within the siliconoxide film formed by the general CVD method. FIG. 9B illustratesconcentration of impurities (H, C, N, Cl) contained within the siliconoxide film formed by the sequence of the current embodiment. In thedrawings, the horizontal axis represents the depth (nm) from the surfaceof the SiO₂ film, and the vertical axis represents concentration(atoms/cm³) of H, C, N, and Cl.

As illustrated in FIGS. 9A and 9B, concentration of H among impuritiescontained within the silicon oxide film formed by the sequence of thecurrent embodiment is identical to concentration of H contained withinthe silicon oxide film formed by the general CVD method. However, it canbe seen that concentration of Cl among impurities contained within thesilicon oxide film formed by the sequence of the current embodiment islower by three digits than concentration of Cl contained within thesilicon oxide film formed by the general CVD method. Also, it can beseen that concentration of N among impurities contained within thesilicon oxide film formed by the sequence of the current embodiment islower by one digit than concentration of N contained within the siliconoxide film formed by the general CVD method. Meanwhile, concentration ofC among the impurities contained within the silicon oxide film formed bythe sequence of the current embodiment and concentration of C containedwithin the silicon oxide film formed by the general CVD method are allbelow the lower detection limit. That is, it can be seen that, whencompared with the silicon oxide film formed by the general CVD method,the silicon oxide film formed by the sequence of the current embodimenthas lower concentration of Cl and N among the impurities, and, amongthem, concentration of Cl is extremely low. Meanwhile, due to thelimitation of the test device used in the second embodiment, N impuritywas incorporated in ppm order within the silicon oxide film formed bythe sequence of the current embodiment. It was confirmed that Nconcentration became a background level (no detection) because the purgegas was changed from N₂ gas to the rare gas such as Ar gas.

Third Embodiment

Next, a third embodiment will be described.

A silicon oxide film was formed on a wafer, where a film containingsilicon atoms and a film containing metal atoms on the surface thereofare exposed, by the sequence of the current embodiment, and SEMobservation of its sectional structure was carried out. Regarding awafer (Si sub) used herein, a silicon oxide film was formed as a gateoxide film (Gate Ox) on the surface of the wafer, and a polycrystallinesilicon film (Poly-Si) and a tungsten film (W) were formed as a gateelectrode on the gate oxide film. Also, a silicon nitride film (SiN) wasformed on the gate electrode. Meanwhile, the film containing siliconatoms is a silicon oxide film, a polycrystalline silicon film, or asilicon nitride film, and the film containing metal atoms is a tungstenfilm. On the wafer, that is, the silicon oxide film, the polycrystallinesilicon film, the tungsten film and the silicon nitride film, thesilicon oxide film was formed as a sidewall spacer by the sequence ofthe current embodiment. In the sequence of the current embodiment, thefilm-forming condition (process condition in each step) was set withinthe condition range of the above-described embodiment. Meanwhile, O₂ gasand H₂ gas were supplied into the process chamber under hydrogen-richcondition, that is, under the condition that the supply flow rate of H₂gas was higher than the supply flow rate of O₂ gas.

The SEM images are shown in FIG. 10A and FIG. 10B. FIG. 10A illustratesthe state of the wafer before the silicon oxide film was formed by thesequence of the current embodiment, and FIG. 10B illustrates the stateof the wafer after the silicon oxide film was formed by the sequence ofthe current embodiment. It can be seen from FIG. 10A and FIG. 10B thatif the silicon oxide film is formed under the above-described processcondition by the sequence of the current embodiment, the silicon oxidefilm can be uniformly deposited on the silicon oxide film, thepolycrystalline film, the tungsten film and the silicon nitride film,without oxidizing the sidewall of the tungsten film.

Fourth Embodiment

Next, a fourth embodiment will be described.

Silicon oxide films were formed by the sequence of the currentembodiment and the general CVD method, and their within-wafer filmthickness uniformities (WIW Unif) were measured. Meanwhile, the generalCVD method is a method that forms a silicon oxide film (HTO film) by aCVD method by supplying DCS and N₂O at the same time, and thefilm-forming temperature was 800° C. Also, in the sequence of thecurrent embodiment, the film-forming temperature was changed in a rangefrom 450° C. to 800° C. The other film-forming conditions (processcondition of each step) were set within the condition ranges of theabove-described embodiment.

The results are illustrated in FIG. 11. FIG. 11 is a graph showing therelationship between the within-wafer film thickness uniformity and thefilm-forming temperature (temperature of the wafer). In FIG. 11, thehorizontal axis represents the film-forming temperature (° C.), and thevertical axis represents the within-wafer film thickness uniformity(arbitrary unit). In FIG. 11, the black circle () represents thewithin-wafer film thickness uniformity of the silicon oxide film formedby the sequence of the current embodiment. Also, the white circle (o)represents the within-wafer film thickness uniformity of the siliconoxide film formed by the general CVD method. Meanwhile, the within-waferfilm thickness uniformity represents the variation degree of thewithin-wafer film thickness distribution, and the within-wafer filmthickness uniformity is considered to be excellent as its value issmaller.

It can be seen from FIG. 11 that, when the film-forming temperature isabove 700° C., the within-wafer film thickness uniformity of the siliconoxide film formed by the sequence of the current embodiment is worsethan the within-wafer film thickness uniformity of the silicon oxidefilm formed by the general CVD method, and, when the film-formingtemperature is 700° C. or less, the within-wafer film thicknessuniformity of the silicon oxide film formed by the sequence of thecurrent embodiment is more excellent than the within-wafer filmthickness uniformity of the silicon oxide film formed by the general CVDmethod. Also, when the film-forming temperature is 650° C. or less, thewithin-wafer film thickness uniformity of the silicon oxide film formedby the sequence of the current embodiment is about ½ of the within-waferfilm thickness uniformity of the silicon oxide film formed by thegeneral CVD method, and, when the film-forming temperature is 630° C. orless, the within-wafer film thickness uniformity of the silicon oxidefilm formed by the sequence of the current embodiment is about ⅓ ofwithin-wafer film thickness uniformity of the silicon oxide film formedby the general CVD method. Hence, it can be seen that the within-waferfilm thickness uniformity is extremely excellent. In particular, it canbe seen that, when the film-forming temperature is 650° C. or less,especially 630° C. or less, the within-wafer film thickness uniformitybecomes remarkably excellent, and furthermore, it becomes stable.

In all these aspects, the film-forming temperature (temperature of thewafer) in the sequence of the current embodiment is preferably 700° C.or less from the viewpoint of the within-wafer film thickness uniformityof the formed silicon oxide film, and more preferably 650° C. or less,specifically 630° C. or less, in order to ensure the better uniformity.

Fifth Embodiment

Next, a fifth embodiment will be described.

Comparison of oxidizing powers was carried out with respect to theoxidation process of the step 3 of the sequence of the currentembodiment (hereinafter, referred to as O₂+H₂-added oxidation process),the case where the oxidation process of the step 3 of the sequence ofthe current embodiment was performed in combination with plasma(hereinafter, referred to as O₂+H₂-added plasma oxidation process), theO₂ plasma oxidation process, the O₃ oxidation process, and the O₂oxidation process. Meanwhile, the O₂+H₂-added plasma oxidation processrefers to a case that performs an oxidation process by activating H₂+O₂with plasma. The oxidizing power was determined by an oxidized siliconamount, that is, a film thickness of a silicon oxide film formed by anoxidization process to silicon. The oxidation process temperature(temperature of the wafer) was changed in a range from 30° C. to 600° C.The other oxidation process conditions were set within the oxidationprocess condition ranges of the step 3 of the above-describedembodiment.

The results are illustrated in FIG. 12. FIG. 12 is a graph showing therelationship between the film thickness of the silicon oxide film andthe oxidation process temperature (temperature of the wafer). In FIG.12, the horizontal axis represents the oxidation process temperature (°C.), and the vertical axis represents the film thickness (Å) of thesilicon oxide film. In FIG. 12, the black circle () represents theoxidized amount by the O₂+H₂-added oxidation process, and the blacktriangle (▴) represents the oxidized amount by the O₂+H₂-added plasmaoxidation process. Also, the black rhombus (♦), the black square (▪),and the white circle (∘) represent the oxidized amounts by the O₂ plasmaoxidation process, the O₃ oxidation process, and the O₂ oxidationprocess, respectively.

It can be seen from FIG. 12 that, at the temperature of 300° C. or less,the oxidized amount by the O₂+H₂-added oxidation process is smaller thanthe oxidized amount by the O₂ plasma oxidation process or the O₃oxidation process, and is equal to the oxidized amount by the O₂oxidation process performed with O₂ alone. However, at the temperatureof above 300° C., especially 350° C. or more, the oxidized amount by theO₂+H₂-added oxidation process is larger than the oxidized amount by theO₂ oxidation process with O₂ alone. Also, at the temperature of 400° C.or more, the oxidized amount by the O₂+H₂-added oxidation process islarger than the oxidized amount by the O₃ oxidation process.Furthermore, it can be seen that, at the temperature of 450° C. or more,the oxidized amount by the O₂+H₂-added oxidation process is larger thanthe oxidized amount by the O₃ oxidation process and the oxidized amountby the O₂ plasma oxidation process.

In these aspects, the film-forming temperature (temperature of thewafer) in the sequence of the current embodiment is preferably 300° C.or more, specifically 350° C. or more, in view of the oxidizing power inthe O₂+H₂-added oxidation process, and more preferably 400° C. or more,specifically 450° C. or more, in order to further improve the oxidizingpower. Meanwhile, in the oxidation process, if the film-formingtemperature is 450° C. or more, it is possible to obtain the oxidizingpower higher than the oxidizing power by the O₃ oxidation process andthe oxidizing power by the O₂ plasma oxidation process. In addition, itwas confirmed in the oxidation process that, at the temperature of 650°C. or 700° C., it is possible to obtain the oxidizing power higher thanthe oxidizing power by the O₃ oxidation process and the oxidizing powerby the O₂ plasma oxidation process.

It is considered that the oxidizing power becomes strong at thetemperature of above 300° C. because of water (H₂O) formed by thereaction of O₂ and H₂, or oxygen having high energy generated at thattime, and diffusion acceleration of oxygen ion (O²⁻) due to diffusion ofhydrogen ion (H⁺) having high diffusion speed into the silicon oxidefilm. Meanwhile, the bond energy of the water (H—O—H) is higher than thebond energy of the oxygen molecule (O—O) or the bond energy of thehydrogen molecule (H—H). It may be said that the state of the waferformed by the bond of oxygen atom and hydrogen atom is more stable thanthe state of the oxygen molecule formed by the bond of oxygen atoms.Also, according to the pressure characteristic inside the furnace, it isapparent that the water is generated by the reaction of O₂ and H₂. Forthese viewpoints, it is considered that the oxidizing power is improvedby the addition of H₂ to O₂.

Meanwhile, at the temperature of 300° C. or more, the oxidized amount bythe O₂+H₂-added plasma oxidation process is larger than the oxidizedamount by the O₂+H₂-added oxidation process, the oxidized amount by theO₃ oxidation process, and the oxidized amount by the O₂ plasma oxidationprocess. Hence, among them, the oxidized amount by the O₂+H₂-addedplasma oxidation process is largest. Therefore, it may be said that theoxidation process of the step 3 in the sequence of the currentembodiment is also effective when it is performed in combination withplasma. Also, it was confirmed that, at the temperature of 650° C. or700° C., the oxidizing power by the O₂+H₂-added plasma oxidation processis higher than the oxidizing power by the O₂+H₂-added oxidation process,and the oxidizing power by the 03 oxidation process, and the oxidizingpower by the O₂ plasma oxidation process. Meanwhile, the oxidationprocess may be performed by activating the addition of H₂ to O₂ withplasma, or the oxidation process may be performed by adding H₂ to O₂plasma, or the oxidation process may be performed by adding H₂ plasma toO₂.

That is, the oxidation process may be performed by activating either orboth of O₂ and H₂ with plasma. In this case, the same effect as theO₂+H₂-added plasma oxidation process can be obtained.

Sixth Embodiment

Next, a sixth embodiment will be described.

Comparison of oxidizing powers was carried out with respect to the casewhere the oxidation process in the step 3 of the sequence of the currentembodiment was performed with N₂O (hereinafter, referred to as N₂Ooxidation process), the case where the oxidation process was performedby adding H₂ to N₂O (hereinafter, referred to as N₂O+H₂ oxidationprocess), and the case where the oxidation process was performed byadding H₂ to NO (hereinafter, referred to as NO+H₂ oxidation process).The comparison of the oxidizing powers was carried out in the samemanner as the fifth embodiment. The oxidation process temperature was600° C., and the other oxidation process conditions were set within theoxidation process condition ranges of the step 3 of the above-describedembodiment.

The results are illustrated in FIG. 13. FIG. 13 is a graph showing therelationship between the film thickness of the silicon oxide film andthe oxidation process temperature (temperature of the wafer). In FIG.13, the horizontal axis represents the oxidation process temperature (°C.), and the vertical axis represents the film thickness (Å) of thesilicon oxide film. In FIG. 13, the white square (□) represents theoxidized amount by the N₂O oxidation process, the white rhombus (⋄)represents the oxidized amount by the N₂O+H₂ oxidation process, and thewhite triangle (Δ) represents the oxidized amount by the NO+H₂ oxidationprocess. Also, in FIG. 13, the experimental results of FIG. 12 are showntogether for comparison. That is, the black circle (), the blacktriangle (▴), the black rhombus (♦), the black square (▪), and the whitecircle (∘) represent the oxidized amount by the O₂+H₂-added oxidationprocess, the oxidized amount by the O₂+H₂-added plasma oxidationprocess, the oxidized amount by the O₂ plasma oxidation process, theoxidized amount by the O₃ oxidation process, and the oxidized amount bythe O₂ oxidation process, respectively.

It can be seen from FIG. 13 that even though H₂ is added to N₂O or NO,the oxidizing power is not improved, and it is substantially equal tothe oxidizing power by the O₂ oxidation process performed with O₂ aloneor the oxidizing power by the N₂O oxidation process performed with N₂Oalone. Also, it can be seen that the same tendency is exhibited when theoxidation process temperature is 300° C., 450° C., 650° C., and 700° C.

From these aspects, in such temperature zones, there is no effect of theoxidizing power improvement even though N₂O or NO is used as theoxygen-containing gas, and the oxygen-containing gas containing nonitrogen (gas that does not contain nitrogen but contains oxygen) needsto be used for obtaining the effect of the oxidizing power improvement.As the oxygen-containing gas containing no nitrogen, a material composedof oxygen atoms alone such as O₃ as well as O₂ may be used. Meanwhile,as described above in the fifth embodiment, gas obtained by activatingO₂ with plasma may be used as the oxygen-containing gas.

Seventh Embodiment

Next, a seventh embodiment will be described.

A silicon oxide film was formed by the sequence of the currentembodiment, and its within-film impurity concentration was measured.Meanwhile, comparison of the within-film impurity concentration,especially N concentration, was carried out with respect to the case ofusing N₂ gas as the purge gas and the case of using Ar gas as the purgegas. In the each step of the sequence of the current embodiment, thefilm-forming temperature was constant at 600° C. and the otherfilm-forming conditions (process condition in each step) were set withinthe condition ranges of the above-described embodiment. Also, themeasurement of impurities inside the film was carried out using SIMS.

The results are illustrated in FIGS. 14A and 14B. FIG. 14A illustratesthe concentrations of impurities (H, C, N, Cl) contained inside thesilicon oxide film when N₂ gas is used as a purge gas. FIG. 14Billustrates the concentrations of impurities (H, C, N, Cl) containedinside the silicon oxide film when Ar gas is used as a purge gas. InFIG. 14A and FIG. 14B, the horizontal axis represents the depth (nm)from the surface of the SiO₂ film, and the vertical axis represents theconcentration (atoms/cm³) of H, C, N, and Cl.

As illustrated in FIGS. 14A and 14B, it can be seen that the case ofusing Ar gas as the purge gas can further reduce N concentration of thesilicon oxide film, compared with the case of using N₂ gas as the purgegas. Meanwhile, in a certain process condition, it could be confirmedthat N concentration became a background level (no detection).

The silicon oxide film formed by the sequence of the current embodiment,as described above, has a small amount of impurity and has superiorquality, compared with the silicon oxide film (HTO film) formed by thegeneral CVD method, and it may be applied to IPD or SWS process of thesemiconductor manufacturing processes by taking advantage of thosecharacteristics.

In addition, in a case where a silicon oxide film is formed usinggeneral amine-based materials such as 3DMAS or BTBAS, a large amount ofC or N impurity exists inside the formed silicon oxide film. In thiscase, a Si-containing layer is formed on a wafer by supplying anamine-based source gas to the wafer, and the Si-containing layer isnitrided by supplying a nitrogen-containing gas activated with plasma orheat to the Si-containing layer. In this way, the Si-containing layer isonce changed to a SiN layer. The SiN layer is changed to an SiO layer bysupplying an oxygen-containing gas activated with plasma or the like tothe SiN layer. By repeating the above processes, an SiO film is formed.Even in this case, impurities such as N easily remain inside the SiOfilm. According to the sequence of the current embodiment, even in thecase of using the amine-based source, an SiO film with a small amount ofN and C impurities inside the film may be formed. Also, as describedabove, it is possible to form the SiO film having the Cl impurity lowerby three digits than the SiO film (HTO film) formed by the general CVDmethod. Furthermore, in the case of using the method that forms theSi-containing layer on the wafer by supplying the source gas to thewafer, once changes the Si-containing layer to the SiN layer bynitriding the Si-containing layer through the supply of thenitrogen-containing gas activated with plasma or heat to theSi-containing layer, changes the SiN layer to the SiO layer by oxidizingthe SiN layer through the supply of the oxygen-containing gas activatedwith plasma or the like to the SiN layer, and forms the SiO film byrepeating the above processes, the oxidation process in the step 3 ofthe sequence of the current embodiment may be performed when the SiNlayer is oxidized and changed to the SiO layer. In such a case, the SiOfilm having a small amount of N and C impurities inside the film can beformed.

Also, in the processing of a gate, for example, after etching a sidewallof a gate, recovery oxidation/selective oxidation by plasma oxidation orhigh-temperature depressurized oxidation is performed and then an SiOfilm as a sidewall spacer is deposited by an ALD method or a CVD method.It was confirmed that, using the sequence of the current embodiment, therecovery oxidation and the deposition of the SiO film as the sidewallspacer could be continuously performed in-situ by optimizing thehydrogen supply amount and time among the oxidation process conditionsof the step 3.

Furthermore, it is required to deposit the SiO film, without oxidizingthe SiN film used as a barrier film. In this case, using the sequence ofthe current embodiment, the hydrogen supply condition or the oxidationprocess time in the step 3 may be optimized, and then, the SiO film maybe deposited under the condition that oxidizes only the Si sourcesupplied in the step 1. Moreover, if the rate is required in this case,the SiO film may be deposited under soft conditions to the extent thatdoes not affect the underlying SiN film, and then, the SiO film may beformed under a condition of a fast rate, that is, a condition of astrong oxidizing power. That is, using the sequence of the currentembodiment, the SiO film may be formed in two steps: first process(initial film-forming process) of forming a first SiO film on anunderlying SiN film under a soft condition of a slow rate, and a secondprocess (main film-forming process) of forming a second SiO film under acondition of a fast rate.

Also, in forming STI liner and embedding, the diffusion-based oxidationand the CVD-based SiO film formation are separately performed. Using thesequence of the current embodiment, they can be continuously performedby changing the conditions of each step, including the film-formingtemperature, to in-situ.

Furthermore, a higher-quality SiO film may be formed by performing aprocess of modifying the film quality of the SiO film, such as thehigh-temperature oxidation and annealing to the SiO film after formingthe SiO film by the sequence of the current embodiment.

Moreover, explanation has been given on the example of forming theSi-containing layer in the step 1 and finally forming the SiO film, inthe sequence of the current embodiment. Instead of the Si-containinglayer (layer containing semiconductor element), a layer containing metalelement such as Ti, Al, and Hf may be formed and then a metal oxide filmmay be finally formed. For example, in the case of forming a TiO film, aTi-containing layer (Ti source adsorption layer or Ti layer) is formedon a wafer in the step 1, and the Ti-containing layer is changed to aTiO layer in the step 3. Also, for example, in the case of forming anAlO film, an Al-containing layer (Al source adsorption layer or Allayer) is formed on a wafer in the step 1, and the Al-containing layeris changed to an AlO layer in the step 3. Also, for example, in the caseof forming an HfO film, an Hf-containing layer (Hf source adsorptionlayer or Hf layer) is formed on a wafer in the step 1, and theHf-containing layer is changed to an HfO layer in the step 3. As such,the sequence of the current embodiment may also be applied to theprocess of forming metal oxides. That is, the sequence of the currentembodiment may also be applied to the case where a predetermined elementis a metal element as well as the case where the predetermined elementis a semiconductor element.

However, in order to perform the oxidation process of the step 3, thatis, in order to generate the oxidizing species containing O such asatomic oxygen by reacting oxygen-containing gas with hydrogen-containinggas under the heated depressurized atmosphere and then perform theoxidation process by using the oxidizing species, at least thetemperature inside the process chamber (temperature of the wafer) mustbe 350° C. or more. At the temperature of less than 350° C., theoxidation process is not performed sufficiently.

In the above embodiment, explanation has been given on the example ofsupplying the O₂ gas, the H₂ gas, and the HCD gas into the processchamber 201 through the different nozzles. As illustrated in FIGS. 15Aand 15B, the O₂ gas and the H₂ gas may be supplied into the processchamber 201 through the same nozzle.

FIG. 15A is a schematic configuration view of a vertical type processfurnace of a substrate processing apparatus that is suitably used inanother embodiment of the present invention, specifically illustrating alongitudinal sectional view of a process furnace 202. Also, FIG. 5B isan A-A′ sectional view of the process furnace 202 illustrated in FIG.15A.

The substrate processing apparatus of the current embodiment isdifferent from the substrate processing apparatus of FIG. 1 and FIG. 2in that a nozzle 233 a is commonly used instead of the first nozzle 233a and the second nozzle 233 b of FIG. 1 and FIG. 2, and a second gassupply pipe 232 b is connected to a first gas supply pipe 232 a. Theother points are identical to those of FIG. 1 and FIG. 2. Meanwhile, inFIGS. 15A and 15B, the same symbols are assigned to the substantiallysame elements as those described in FIG. 1 and FIG. 2, and theirdescription will be omitted.

In the current embodiment, O₂ gas and H₂ gas are mixed within the firstgas supply pipe 232 a and the nozzle 233 a and supplied into the processchamber 201. In this case, the inside of the nozzle 233 a is heated tothe same temperature as the inside of the process chamber 201.Therefore, the O₂ gas and the H₂ gas react with each other within thenozzle 233 a that is under a pressure atmosphere less than theatmospheric pressure, and oxidizing species containing oxygen isgenerated within the nozzle 233 a. Furthermore, the pressure inside thenozzle 233 a is higher than the pressure inside the process chamber 201.Hence, the reaction of the O₂ gas and the H₂ gas within the nozzle 233 ais accelerated, and a lager amount of oxidizing species is generated bythe reaction of the O₂ gas and the H₂ gas, thereby further improvingoxidizing power is obtained. Moreover, since the O₂ gas and the H₂ gasare uniformly mixed within the nozzle 233 a before being supplied intothe process chamber 201, the O₂ gas and the H₂ gas uniformly react witheach other within the nozzle 233 a, and the concentration of theoxidizing species becomes uniform, whereby the oxidizing power betweenthe wafers 200 becomes uniform.

In these aspects, it is preferable that the O₂ gas and the H₂ gas aresupplied into the process chamber 201 through the same nozzle in orderto obtain the effect of high oxidizing power improvement and the effectof oxidizing power uniformity.

The method of manufacturing the semiconductor device and the substrateprocessing apparatus in accordance with the embodiments of the presentinvention are capable of forming the insulation film having extremelylow impurity concentrations of carbon, hydrogen, nitrogen, chlorine andso on inside the film at a low temperature

The following description will be made on complementary notes ofpreferred embodiments of the present invention.

In accordance with an embodiment of the present invention, there isprovided a method of manufacturing a semiconductor device, the methodincluding: forming an oxide film having a predetermined film thicknesson a substrate by repeating a process of forming a predeterminedelement-containing layer on the substrate by supplying source gascontaining a predetermined element into a process vessel accommodatingthe substrate, and a process of changing the predeterminedelement-containing layer to an oxide layer by supplyingoxygen-containing gas and hydrogen-containing gas into the processvessel that is set below atmospheric pressure, wherein theoxygen-containing gas is oxygen gas or ozone gas, thehydrogen-containing gas is hydrogen gas or deuterium gas, and thetemperature of the substrate is in a range from 400° C. or more to 700°C. or less in the process of forming the oxide film.

Preferably, the temperature of the substrate is in a range from 450° C.or more to 700° C. or less in the process of forming the oxide film.

Preferably, the temperature of the substrate is in a range from 450° C.or more to 650° C. or less in the process of forming the oxide film.

Preferably, the temperature of the substrate is kept at a constanttemperature in the process of forming the oxide film.

Preferably, in the process of changing the predeterminedelement-containing layer to the oxide layer, the oxygen-containing gasand the hydrogen-containing gas are supplied through the same nozzle.

Preferably, in the process of changing the predeterminedelement-containing layer to the oxide layer, oxidizing speciescontaining oxygen is generated by reacting the oxygen-containing gaswith the hydrogen-containing gas within the process vessel that is undera pressure atmosphere less than the atmospheric pressure, and thepredetermined element-containing layer is oxidized by the oxidizingspecies and changed to the oxide layer.

Preferably, the predetermined element is a semiconductor element or ametal element.

Preferably, while repeating the process of forming the predeterminedelement-containing layer and the process of changing the predeterminedelement-containing layer to the oxide layer, the inside of the processvessel is gas-purged by using inert gas containing no nitrogen.

Preferably, the inert gas containing no nitrogen is a rare gas.

Preferably, in the process of forming the predeterminedelement-containing layer, the hydrogen-containing gas is supplied intothe process vessel together with the source gas.

Preferably, in the process of forming the oxide film, thehydrogen-containing gas is always supplied into the process vessel.

Preferably, the oxygen-containing gas is oxygen gas, and thehydrogen-containing gas is hydrogen gas.

In accordance with another embodiment of the present invention, there isprovided a method of manufacturing a semiconductor device, the methodincluding: forming a silicon oxide film having a predetermined filmthickness on a substrate by repeating a process of forming asilicon-containing layer on the substrate by supplying source gascontaining silicon into a process vessel accommodating the substrate,and a process of changing the silicon-containing layer to a siliconoxide layer by supplying oxygen-containing gas and hydrogen-containinggas into the process vessel that is set below atmospheric pressure,wherein the oxygen-containing gas is oxygen gas or ozone gas, thehydrogen-containing gas is hydrogen gas or deuterium gas, and thetemperature of the substrate is in a range from 400° C. or more to 700°C. or less in the process of forming the silicon oxide film.

In accordance with another embodiment of the present invention, there isprovided a method of manufacturing a semiconductor device, the methodincluding: forming a silicon oxide film having a predetermined filmthickness on a substrate by repeating a process of forming asilicon-containing layer on the substrate by supplying source gascontaining silicon into a process vessel accommodating the substratewhere a film containing silicon atoms and a film containing metal atomson the surface thereof are exposed, and a process of changing thesilicon-containing layer to a silicon oxide layer by supplyingoxygen-containing gas and hydrogen-containing gas into the processvessel that is set below atmospheric pressure, such that a supply flowrate of the hydrogen-containing gas is higher than a supply flow rate ofthe oxygen-containing gas, wherein the oxygen-containing gas is oxygengas or ozone gas, the hydrogen-containing gas is hydrogen gas ordeuterium gas, and the temperature of the substrate is in a range from400° C. or more to 700° C. or less in the process of forming the siliconoxide film.

Preferably, the film containing the metal atoms is a tungsten film.

In accordance with another embodiment of the present invention, there isprovided a substrate processing apparatus including: a process vesselconfigured to accommodate a substrate; a heater configured to heat theinside of the process vessel; a source gas supply system configured tosupply source gas containing a predetermined element into the processvessel; an oxygen-containing gas supply system configured to supplyoxygen gas or ozone gas as the oxygen-containing gas into the processvessel; a hydrogen-containing gas supply system configured to supplyhydrogen gas or deuterium gas as the hydrogen-containing gas into theprocess vessel; a pressure regulation unit configured to regulatepressure inside the process vessel; and a controller configured tocontrol the source gas supply system, the oxygen-containing gas supplysystem, the hydrogen-containing gas supply system, the pressureregulation unit, and the heater to so that an oxide film having apredetermined film thickness is formed on the substrate by repeating aprocess of forming a predetermined element-containing layer on thesubstrate by supplying the source gas into the process vesselaccommodating the substrate, and a process of changing the predeterminedelement-containing layer to an oxide layer by supplying theoxygen-containing gas and the hydrogen-containing gas into the processvessel that is set below atmospheric pressure, and so that thetemperature of the substrate is set in a range from 400° C. or more to700° C. or less when forming the oxide film.

In accordance with another embodiment of the present invention, there isprovided a substrate processing apparatus including: a process vesselconfigured to accommodate a substrate; a heater configured to heat theinside of the process vessel; a source gas supply system configured tosupply source gas containing silicon into the process vessel; anoxygen-containing gas supply system configured to supply oxygen gas orozone gas as the oxygen-containing gas into the process vessel; ahydrogen-containing gas supply system configured to supply hydrogen gasor deuterium gas as the hydrogen-containing gas into the process vessel;a pressure regulation unit configured to regulate pressure inside theprocess vessel; and a controller configured to control the source gassupply system, the oxygen-containing gas supply system, thehydrogen-containing gas supply system, the pressure regulation unit, andthe heater so that a silicon oxide film having a predetermined filmthickness is formed on the substrate by repeating a process of forming asilicon-containing layer on the substrate by supplying the source gasinto the process vessel accommodating the substrate, and a process ofchanging the silicon-containing layer to a silicon oxide layer bysupplying the oxygen-containing gas and the hydrogen-containing gas intothe process vessel that is set below atmospheric pressure, and so thatthe temperature of the substrate is set in a range from 400° C. or moreto 700° C. or less when forming the silicon oxide film.

In accordance with another embodiment of the present invention, there isprovided a substrate processing apparatus including: a process vesselconfigured to accommodate a substrate; a heater configured to heat theinside of the process vessel; a source gas supply system configured tosupply source gas containing silicon into the process vessel; anoxygen-containing gas supply system configured to supply oxygen gas orozone gas as the oxygen-containing gas into the process vessel; ahydrogen-containing gas supply system configured to supply hydrogen gasor deuterium gas as the hydrogen-containing gas into the process vessel;a pressure regulation unit configured to regulate pressure inside theprocess vessel; and a controller configured to control the source gassupply system, the oxygen-containing gas supply system, thehydrogen-containing gas supply system, the pressure regulation unit, andthe heater so that a silicon oxide film having a predetermined filmthickness is formed on the substrate by repeating a process of forming asilicon-containing layer on the substrate by supplying the source gasinto the process vessel accommodating the substrate where a filmcontaining silicon atoms and a film containing metal atoms on thesurface thereof are exposed, and a process of changing thesilicon-containing layer to a silicon oxide layer by supplying theoxygen-containing gas and the hydrogen-containing gas into the processvessel that is set below atmospheric pressure, such that a supply flowrate of the hydrogen-containing gas is higher than a supply flow rate ofthe oxygen-containing gas, and so that the temperature of the substrateis set in a range from 400° C. or more to 700° C. or less when formingthe silicon oxide film.

Preferably, the substrate processing apparatus further includes a commonnozzle configured to supply the oxygen-containing gas, which is suppliedfrom the oxygen-containing gas supply system, and thehydrogen-containing gas, which is supplied from the hydrogen-containinggas supply system, into the process vessel.

What is claimed is:
 1. A method of manufacturing a semiconductor device,the method comprising: forming an oxide film on a substrate byalternately repeating: (a) forming an element-containing layer on thesubstrate by supplying a source gas containing an element into a processvessel accommodating the substrate through a first nozzle; and (b)changing the element-containing layer to an oxide layer by:simultaneously supplying an oxygen-containing gas through a secondnozzle and a hydrogen-containing gas through a third nozzle into theprocess vessel having an inside pressure lower than atmosphericpressure; mixing and reacting the oxygen-containing gas with thehydrogen-containing gas in a non-plasma atmosphere within the processvessel to generate an atomic oxygen; and oxidizing theelement-containing layer by the atomic oxygen; wherein the (a) and the(b) are performed while heating the substrate, an inside of the processvessel, an inside of the first nozzle, an inside of the second nozzleand an inside of the third nozzle to a temperature equal to afilm-forming temperature.
 2. The method of claim 1, wherein thetemperature is a self-decomposing temperature of the source gas.
 3. Themethod of claim 1, wherein the (a) comprises forming theelement-containing layer having a thickness of several atomic layers onthe substrate by supplying the source gas into the process vesselaccommodating the substrate under a condition where the source gas isself-decomposed.
 4. The method of claim 1, wherein the temperature is atemperature where the source gas is not self-decomposed.
 5. The methodof claim 1, wherein the (a) comprises forming the element-containinglayer having a thickness of less than one atomic layer on the substrateby supplying the source gas into the process vessel accommodating thesubstrate under a condition where the source gas is not self-decomposed.6. The method of claim 1, wherein the (a) comprises forming adiscontinuous element-containing layer on the substrate by supplying thesource gas into the process vessel accommodating the substrate under acondition where the source gas is not self-decomposed.
 7. The method ofclaim 1, wherein the oxygen-containing gas comprises oxygen gas or ozonegas and the hydrogen-containing gas comprises hydrogen gas or deuteriumgas.
 8. The method of claim 1, wherein the element comprises asemiconductor element or a metal element.
 9. The method of claim 1,wherein the element comprises silicon.
 10. The method of claim 1,wherein the first nozzle, the second nozzle and the third nozzle differfrom one another.
 11. The method of claim 1, wherein the first nozzleand the second nozzle differ from each other, and the first nozzle andthe third nozzle are same nozzles.
 12. The method of claim 1, whereinthe first nozzle and the second nozzle differ from each other, and thesecond nozzle and the third nozzle are same nozzles.
 13. A method ofmanufacturing a semiconductor device, the method comprising: forming asilicon oxide film on a substrate by alternately repeating: (a) forminga silicon layer on the substrate by supplying a source gas containingsilicon into a process vessel accommodating the substrate through afirst nozzle; and (b) changing the silicon layer to a silicon oxidelayer by: simultaneously supplying an oxygen-containing gas through asecond nozzle and a hydrogen-containing gas through a third nozzle intothe process vessel having an inside pressure lower than atmosphericpressure; mixing and reacting the oxygen-containing gas with thehydrogen-containing gas in a non-plasma atmosphere within the processvessel to generate an atomic oxygen; and oxidizing the silicon layer bythe atomic oxygen, wherein the (a) and the (b) are performed whileheating the substrate, an inside of the process vessel, an inside of thefirst nozzle, an inside of the second nozzle and an inside of the thirdnozzle to a temperature equal to a film-forming temperature.
 14. Themethod of claim 9, wherein the element-containing layer comprises aSi—Si bond and at least one selected from a group consisting of a Si—Clbond, a Si—N bond, a Si—H bond and a Si—C bond, and the (b) comprisessupplying the element-containing layer with an energy capable ofbreaking the Si—Cl bond, the Si—N bond, the Si—H bond and the Si—C bondwithout breaking the Si—Si bond.
 15. The method of claim 9, wherein theelement-containing layer comprises a Si—Si bond and a Si—Cl bond, andthe (b) comprises supplying the element-containing layer with an energycapable of breaking the Si—Cl bond without breaking the Si—Si bond. 16.The method of claim 9, wherein the element-containing layer comprises aSi—Si bond, a Si—H bond and a Si—Cl bond, and the (b) comprisessupplying the element-containing layer with an energy capable ofbreaking the Si—H bond and the Si—Cl bond without breaking the Si—Sibond.
 17. The method of claim 1, wherein the element-containing layercomprises a Si—Si bond, a Si—N bond and a Si—H bond, and the (b)comprises supplying the element-containing layer with an energy capableof breaking the Si—N bond and the Si—H bond without breaking the Si—Sibond.
 18. A substrate processing apparatus comprising: a process vesselconfigured to accommodate a substrate; a heater configured to heat thesubstrate accommodated in the process vessel; a source gas supply systemconfigured to supply a source gas containing an element into the processvessel via a first nozzle; an oxygen-containing gas supply systemconfigured to supply an oxygen-containing gas into the process vesselthrough a second nozzle; a hydrogen-containing gas supply systemconfigured to supply a hydrogen-containing gas into the process vesselthrough a third nozzle; a pressure regulation unit configured toregulate an inside pressure of the process vessel; and a controllerconfigured to control the heater, the source gas supply system, theoxygen-containing gas supply system, the hydrogen-containing gas supplysystem and the pressure regulation unit to form an oxide film on thesubstrate by alternately repeating: (a) forming an element-containinglayer on the substrate by supplying the source gas into the processvessel accommodating the substrate through the first nozzle; and (b)changing the element-containing layer to an oxide layer by:simultaneously supplying the oxygen-containing gas through the secondnozzle and the hydrogen-containing gas through the third nozzle into theprocess vessel having an inside pressure lower than atmosphericpressure; mixing and reacting the oxygen-containing gas with thehydrogen-containing gas in a non-plasma atmosphere within the processvessel to generate an atomic oxygen; and oxidizing theelement-containing layer by the atomic oxygen; wherein the (a) and the(b) are performed while heating the substrate, an inside of the processvessel, an inside of the first nozzle, an inside of the second nozzleand an inside of the third nozzle to a temperature equal to afilm-forming temperature.